Number of distinct permutation a String can have | C # program to find number of distinct permutations of a string . ; Utility function to find factorial of n . ; Returns count of distinct permutations of str . ; finding frequency of all the lower case alphabet and storing them in array of integer ; finding factorial of number of appearances and multiplying them since they are repeating alphabets ; finding factorial of size of string and dividing it by factorial found after multiplying ; Driver code
using System ; public class GFG { static int MAX_CHAR = 26 ; static int factorial ( int n ) { int fact = 1 ; for ( int i = 2 ; i <= n ; i ++ ) fact = fact * i ; return fact ; } static int countDistinctPermutations ( String str ) { int length = str . Length ; int [ ] freq = new int [ MAX_CHAR ] ; for ( int i = 0 ; i < length ; i ++ ) if ( str [ i ] >= ' a ' ) freq [ str [ i ] - ' a ' ] ++ ; int fact = 1 ; for ( int i = 0 ; i < MAX_CHAR ; i ++ ) fact = fact * factorial ( freq [ i ] ) ; return factorial ( length ) / fact ; } public static void Main ( String [ ] args ) { String str = " fvvfhvgv " ; Console . Write ( countDistinctPermutations ( str ) ) ; } }